Do-it-yourself canvases are hot, in both craft stores and collections

Not quite art yet not entirely craft, paint-by-number kits were all the rage during the 1950s and '60s. Originated by artist Dan Robbins, who took his cue from Leonardo da Vinci's practice of assigning numbered sections of his paintings to apprentices, the kits made it easy for the masses to create mountain vistas or the Last Supper. After the craze died down, the kits were left to gather dust on the back shelves of craft stores.

But interest in all things paint by number resurfaced a few years ago, and the fad seems to be gaining steam. Vintage finished pictures are...